I've seen it so many times in the movies and TV: a person wakes up in this futuristic world, walks by his kitchen, and a computerized voice is telling him that someone is calling him. But instead of picking up a receiver, the call is actually a video-call, and his TV is used for the conversation. If you put 2 and 2 together, this is not really that futuristic. Having a camera attached on your TV, and a VoIP SIP or Skype connection with it, is not mad science. So why don't we already have this on our TVs?

Money money money money money. Too many companies want to charge too much money for their slice of the pie. The telcos don't want to be dumb pipes, the TV manufacturers want to distinguish themselves from other TV sets and so don't want interoperability, the software vendors want market dominance for their brand, so also don't want interoperability (e.g. Skype).